Liquid pressure remote control system



J. K. SIMPSON 2,408,003

LIQUID PRESSURE REMOTE CONTROL SYSTEM Sept. 24, 1946.

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LIQUID PRESSURE REMOTE CONTROL SYSTEM J. K. SIMPSON Filed Jan. 5, 1944 4 Sheets-Sheet 2 Sept. 24, 1946. J. K. SIMPSON 2,403,003

LIQUID PRESSURE REMOTE CONTROL SYSTEM Filed Jan. 3, 1944 4 Sheets-Sheet 5 Patented Sept. 24, 1946 LIQUID# PRESSURE REMOTE CONTROL t SYSTEM John Keith Simpson, Leamington Spa, England,

assignor to Automotive Products Company Limited, Leamington Spa, England Application January 3, 1944, Serial No. 516,863 In Great Britain November 12, 1942 16 Claims. l

This invention relates to liquid pressure remote control systems, and more specifically to that type of remote control system in which a transmitter piston is movable in a cylinder to eject liquid from the cylinder through a pipeline into a motor cylinder and so to produce corresponding movement of a piston in the motor cylinder. Y

The primary object of the invention is to provide an improved means for periodically correctting the phase relation of the transmitter and motor pistons, in order to compensate for eX- pansion and contraction of the liquid due to temperature variations, and for leakage from the system. Another object is to provide transmitter and motor units each constitutingelements of two separate remote control systems, operable together or separately to produce different movements of a controlled element'.

According to one aspect of the invention, in a liquid pressure remote control system of the type referred to, the movement ci the transmitter piston to at least one end of the transmitter cylinder opens a .valve connecting that end of the transmitter cylinder to a source of liquid under pressure, whereby the stroke of the motor piston, if, due to leakage o1' other causes it has not been completed by the movement of the transmitter piston, is completed by liquid from the said source.

According to another aspect of the invention, a liquid pressure remote control system of the type referred to, comprises a transmitter cylinder, a motor cylinder, pistons in the said cylinders, means for producing movement of the transmitter piston in the transmitter cylinder, and a Valve device operated by the movement-producing means when the transmitter piston reaches at least one end of its stroke, to connect the motor cylinder to a source of liquid under pressure in such a way that the pressure from the said source tends to move the motor piston in the same direction as it has been moved by the liquid from the transmitter cylinder during the stroke of the latter just completed.

A double acting liquid pressure remote control system of the type referred to may comprise a transmitter cylinder, a motor cylinder, pistons in the cylinders, and two pipe-lines each connecting one end of the transmitter cylinder to one end of the motor cylinder, the movement of the transmitter piston to either end of the transmitter cylinder actuating a valve to connect that end of the transmitter cylinder to a source of liquid under pressure and to connect the other 2 Y end of the transmitter cylinder to a drain or reservoir, whereby the liquid from said source tends to move the motor piston in the same direction as it has been moved by liquid from the transmitter cylinder during the stroke of the latter just completed.

In a liquid pressure remote control system according to the lastpreceding paragraph, the effective area of each end of the transmitter piston may be equal to the effective area of that end of the motor piston upon which liquid ejected from the transmitter cylinder by that end of the transmitter piston acts, the total stroke of the transmitter piston being greater than the stroke of the motor piston, and that part of the stroke of vthe transmitter piston during which neither end of the transmitter cylinder is connected to the source of liquid under pressure being equal to the stroke of the motor piston.

In a liquid pressure remote control system of the type referred to having the motor piston movable in one direction by liquid pressure and in the other direction by a spring, valve means may be'provided to connect the liquid-containing part of the system to a source of liquid under pressure When the transmitter piston is at the end of the stroke during which it transfers liquid to the motor cylinder, and to connect the said part of the systemto a reservoir or drain when the transmitter piston is at the other end of its stroke.

According to a further aspect of the invention, in a liquid pressure remote control system of the type referred to, a piston reciprocable in a transmitter cylinder is hollow and itself forms a cylinder for a second piston reciprocable therein, the transmitter unit being connected by conduits to motorV cylinders the pistons in which are operated by the inner and outer pistons of the transmitter unit respectively, and means being provided to move the transmitter pistons together or separately, to produce movement of one or other of the motor pistons relative to the cylinder inY which it is mounted.

In a liquid pressure remote control system as set out in the last preceding paragraph, the motor cylinders may comprise a single unit similar to the transmitter, one piston being hollow to form the cylinder for the second piston.

A liquid pressure remote control system as set by and moving with the transmitter piston rod I3. Within the bore 28 the rod 48 is surrounded by a spring 52 extending between two washers 53, 53, the rod having abutments e, 55 to be engaged bythe washers and to limit the extension y ofthe spring. A reduced portion of the bore 28 The invention is hereinafter described with rcference to the accompanying drawings, in which:

Figure 1 shows in diagrammatic form twopipe-line liquid pressure remote control system according to the invention; v

Figure 2 shows, also in diagrammatic a single-pipe-line liquid pressure remote control system according to the invention;

Figure 3 shows the transmitter' and receiver units of a modified form of liquid pressure remote control system according to the invention;

Figure 4 is an isometricview showing the transmitter unit of the system shown in Figure 3 coupled to one of two devices which are to be operated in synchronism; and

Figure 5 is a diagram relating to one method of employing the system shown in Figure 3.

Referring to Figure 1, the transmitter and motor units are shown at A and B respectively. The transmitter comprises a body ifi having a cylinder bore I l therein to receive a piston l2, the piston rod I3 of which projects from the body is and carries a member I4 for connection to an operating lever or equivalent (not shown).

VThe motor unit comprises a cylinder i5 in which there is slidable a piston Ai5 having a rod Il of the same diameter as the transmitter piston rod, to which is attached a member i8 for oonnection to the device to be operated.

The cylinder boreV I I in the transmitter unit, and the bore of the motor cylinder i5 are of the same diameter, 'and each is divided by its piston into two chambers, one of the fullbore of the cylinderand the other of'an effective area equal to the cylinder bore less the' area of the piston rod., The two chambers in the transmitter cylin-l derjare indicated Aby the references i8 and i9 respectively, i8 being the annular chamber, and the two chambers inthe motor cylinder are indicated by the references and 2i respectively, 2e being the annular chamber. Ports 22 and 23 leading to the Vchambers i8 and 2e respectively are connected by a pipe 24, and ports 25 and 23 leading to the chambers i9 and 2l respectivelyare connected by a pipe 2l.

' The transmitter body lil also contains a bore 28 to accommodate a piston valve 29. The bore 28 is parallel to thecylinder bore il, and has fixed therein at one end a sleevevz'i in which are four longitudinally spaced ports 3i, .'32, 33 and 34. The port 3i is connected by a passage 35 in the body I9 to the annular chamber i8 in the cylinder I I, and the port 33 is similarly connected by a passage 36 to the chamber I9. The intermediate port 32 is connected by a pipe Si to a liquid pressure accumulator 38, and the fourth. port 34 is connected by a pipe 39 to a liquid reservoir liti. The ports 3| and 33 are equidistant from the port 32. The piston valve 29 has two lands el and l2 oi equal length separated by an annular recess t3, theland M being bounded on its opposite side by a second annular recess M connected by passages and'li to the end face 4l of the valve piston. From the end of the valve piston nearer'the'recess Vi4 there extends a rod i8 which projects from Athe body I0 andV carries two stops 49 and 59, between which `the rod passes freely through a hole in an arm 5I carried terminates in a shoulder 5t spaced from the end 5l of the sleeve 2t by a distance equal to the spacing of the abutments 54, 55, and the washers it-project radially beyond the abutments 515, 55 to engage the shoulder and the end 5l of the sleeve respectively. The valve piston 23 isy thus biased to a central position by the spring, but can be moved in either direction from that position. The arrangement is such that with the valve piston 29 in the position to which it is tween the transmitter cylinder Ii and the ac moved bythe spring, the ports Si and 33 are covered by the lands 4I and G2 on the valve piston, movement of the piston in either direction bringing one or `other of the ports 3l and 33 into communication with the recess i3 in the piston, so that that portV is connected to the port 32 and to the accumulator 33, and simultaneously bringing the other port S or 33 into communication witheitherv the recess $4 or the bore of the sleeve 3Q beyond the end 41 of the valve piston, so that that port is connected 'to the port 34 and so to the reservoir 4i).

The arrangement is' such that as 'the' transmitter piston i2 approaches either end of'its stroke, the arm 5I engages the 'stop 'it ror Eil and moves the lvalve piston from its central posi tion to make the appropriate connections be cumulator S8 and reservoir 4i), as described below. The total stroke of the transmitter piston l2 is greater .than the total stroke of the receiver piston-iii', the stroke of the latter piston being equal to the part of the stroke of the transmitter piston between'the points at which the ports 3i and commence to be opened bymovement` of the pistonvalve 25. M 1 The accumulator 33 is suppiied with liquid under pressure by a continuously driven pump 5i! which draws liquid fromY the reservoirll, a cutout valve 59 being provided to connect thepump to the accumulator when the vpressure in the iatter falls below a' predetermined' minimum, and to disconnect the pumpffrom the accumulator and allow it to circulate liquid idly back to the reservoir when the pressure in the accumulator rises to a predetermined maximum. l Y J VThe system above described is shown in Figure 1 withboth pistons at one end of their strokes, so that the-chambers I8 and 2| in the transmitter and receiver units respectively have vtheir maaimum volume, and the chambers l and 2B their minimunivoiume. The-arm 5i is in engagement with the stop 5t, and the piston valve is so positioned that the port 33 is connected to the port 32, and to the accumulator, whilst the port tl is connected to the port 3ft', and to the reservoir.- v

This is the condition which exists when the transmitter 4piston I2 has completed its stroke towards the right as shown on the drawings, and it will be evident that should there have been any leakage or contraction of the liquid in that part of the system comprising the chambers I9 and 2IV and the pipe 2l which would result in the piston I6 lagging behind the piston i2, the stroke of the piston it would `be completed by pressure from the accumulator after the piston valve 2t has moved to connect the ports 32 and 33, whilst any excess liquid in the part of the system comprising the chambers I8 and 2B and the pipe 24 would bejected through the passage 35, and ports 3| and 34, to the reservoir. Movement of the transmitter piston to the opposite end of its stroke moves the valve piston 29 to connect the port 3| to the port 32, and the port 33 to the port 35, thus permitting liquid from the accumulator to enter the part of the system comprising chambers i8 and 23 and pipe 2li, and connecting the part of the system comprising chambers i3 and 2| and pipe 21 to the reservoir, and so ensuring that the stroke of the motor piston in that direction is completed. So long as the transmitter piston moves in that part of its travel between the points where the valve 29 begins to open the ports 3l and 33, the system is completely closed.

The system shown in Figure 2 isof the singlepipe-line type, the pistons and B2 of the transmitter unit C and motor unit D respectively operating in cylinders E?, and 3i! connected by a single pipe 35, and being held up against the liquid column in that pipe and the cylindersby springs 65 and 31. The piston rods are provided with coupling members E3 and 39 respectively for connection to an operating lever or equivalent, and to the device to be operated. The body 13 of the transmitter unit C is formed with bore 1i for a piston valve 12 controlling the connection between a single port 13 connected by a passage 'a'liwith the transmitter cylinder and either of two ports 15 and 16, the port 15 being connected by a pipe 11 to a liquid pressure accumulator 18 and the port 15 being connected by a pipe 19 to a liquid reservoir 83, A land 3| on the valve piston 12 separates an annular recess 82 in the valve piston from the end of the piston, the ports i5 and 13 being respectively in permanent communication with the recess 82 and the valve bore 1| beyond the end of the piston. The port 13 lies midway between the ports 13 and 13, being covered by the land 3| when the valve piston is in a central position. The valve piston is biassed to a central position by a spring S3 similar to the spring 52 of Figure l, and is similarly displaced when the transmitter piston reaches either end of its stroke, by the engagement of an arm 34 carried by the rod of the transmitter piston with one of two stops |35 and 86 on the valve rod 81.

The pressure in the accumulator is maintained by a pump S8 and cut-out valve 39 as described in connection with Figure l.

In the system just described, when the transmitter piston 3l is moved to the end of its stroke during which it forces liquid into the motor` cylinder, the valve piston l2 is moved toa position in which it connects the ports 13 and 15, so that liquid from the accumulator 13 can enter the system, and complete the stroke of the motor piston 32 if, due to leakage or contraction of the liquid, this stroke has not been completed. The parts are then in the position shown in Figure 2. During the movement of the transmitter piston away from the position shown, the spring 31 causes the motor piston to follow up the movement of the transmitter piston. If there were an excess of liquid in the system, the motor piston 32 would not be able to complete this stroke, but the nal movement of the transmitter piston 6| in this direction moves the valve piston 12 to connect the port 'i3 to the port 1G, thus connecting the system to the reservoir 83, so that the spring E1 can force liquid out of the system to the reservoir, and complete the stroke of thepiston 32. As in the case of the systemshown in Figure 1,

6 the stroke of the motor piston 62 is shorter than the total stroke of the transmitter piston 9|, the area of the pistons being equal, and the stroke of the motor piston is equal to the stroke of the transmitter piston between the points at which the valve commences to open the port 13.

Figure 3 shows what may be termed a dual remote control system, in which the transmitter unit and motor unit each include the elements of two separate systems. The transmitter unit is indicated :by the reference E and the motor unit by the reference F. The transmitter unit comprises a body 3| in which is mounted a sleeve 92 forming the cylinder -for a hollow piston 93 which itself forms the cylinder for a second piston 94 hereinafter referred to as the inner piston. From one end of the hollow piston 93 there extends a tubular piston rod 95, through which passes the rod 96 of the inner piston 94, the rod 96 being of sumcient length to project beyond the outer end of the hollow rod 35 whatever may be the position of the inner piston 34 in the hollow piston 93.

The motor unit comprises a cylinder 91 in which is slidably mounted a hollow piston 38 itself forming a `cylinder for an inner piston 99. As in the transmitter unit, the hollow piston 9B has a tubular piston rod |99 through which extends the piston rod `||'i| of the inner piston 99.

Two piston valves |02 and |33 are arranged in rbores |34 and |05 in the body 9|, each valve being identical with the valve 29 shown in Figure l, and having a similar centering spring |55. The piston valve 32 controls the connections between ports |31, |53, |39 and H0, the ports |01 :and |39 being lconnected by passages and H2 to longitudinal grooves ||3 and H4 in the outer surface of the sleeve 32, the grooves being connected by ports H5 and ||6 at the centre of the length of the sleeve to further longitudinal grooves ||1 and |3 in the outer surface of the hollow piston, from which grooves ports IIB and |20 lead respectively into opposite ends of the hollow piston. The piston valve |53 controls the `connections between ports |2|, |22, |23 and |24, the ports |2| and |23 being connected by passages |25 and |26 to opposite ends of the main transmitter cylinder formed by the sleeve 92. A pipe |21 connected to the ports |58 and |22 leads to a liquid pressure accumulator (not shown), and a pipe |28 yconnected to the ports III] and |24 leads to a liquid reservoir, also not shown, the liquid pressure and accumulator being coupled up with a pump and cut-out valve as shown in Figure 1.

The connections between the transmitter and motor units are as follows, the left and right hand ends of the various parts being as shown on the drawings. The left hand end of the transmitter cylinder (the sleeve 92) is connected to the left hand end of the motor cylinder 91 by the passage |25, an annular groove |29 around the sleeve |30 of the piston valve |03, and a pipe |3|. The right hand end of the transmitter cylinder is connected to the right hand end of the motor cylinder 91 by the passage |26, a branch passage |32 and a pipe |33. The left hand end of the hollow transmitter piston 93 is connected to the left hand end of the hollow motor piston 38 by way oi the port H9, groove H1, port H5, groove |I3, passage an annular groove |34 around the sleeve |35 of the piston valve |32, a pipe |33, a port |311 in the wall of the motor :cylinder 91, a longitudinal groove |38 in the outer surface of the hollow motor piston 33, and a port |39 in the wall of that piston. The right hand end of the hollow transmitter lpiston is connected to the right hand end. of: theY hollow motor piston by the port |279, groove H8, port Ilo, groove H4, passage H2, a branchpassage |493, a pipe I 4|, a port |42 in the wall of the motor cylinder 91, a longitudinal groove |43 in the outer surface of the hollow motor piston SS, and a port |44 in the wall of that piston. The valve |03 is operated by an arm |65 carried by the tubular piston rod e and apertured to slide between stops |58; andI |5| on the rod |52 which carries the valve |03 so that the valve piston les ismoved to connect one or other end of the transmitter cylinder (the sleeve 92) to the liquid pressure accumulator and the other end thereof to the reservoir, whenever the hollow piston'cfi reaches either end of its stroke. The valve ||l2 is operated by. a bent arm M9 carried by the piston rod 95 and apertured to slide between stops It and |41 on the Valve rod |48 which carries the valve |02, the stops being so spaced that the valve is operated only when both the hollow piston 93 and the inner piston 94 are at the sameiend of their strokes. Rotation of the hollow pistons 93 and 98 is prevented, in order to keep the grooves in the said pistons in register with the ports in the transmitter and receiver i cylinders, rotation of the hollow transmitter piston being prevented by the Valve operating arm |45, and rotation of the hollow receiver piston 88 being prevented by an arm |53 having an aperture through which passes a rod` |54 fixed to the cylinder 91.

Each individual system of the dual system shown in Figure 3 operates in exactly the same manner as the system shown in Figure 1, except that the system comprising the inner pistons 95|, S9 and the cylinders formed within the hollow pistons 93 and 98 (which may be termed the inner system) is connected to the accumulator and reservoir only when the hollow transmitter piston Q3 as well as the inner piston 94 is at the end of its stroke, both pistons being at the same end of their strokes. It will be evident that this modification must be made to avoid connection of the inner system with the accumulator and reservoir when the piston 94 is not at the end of its stroke.

In the drawings, the hollow piston 93 is shown at the right-hand end of its stroke, the valve H33 having consequently been moved to connect the ports E22, 23 together, and to connect the ports I2! and |24 together, so that pressure from the accumulator acts upon the hollow motor piston Q3 to ensure that the stroke of that piston is completed. rThe inner transmitter piston 95 and the inner motor piston 9,9 are between the ends of their strokes, and the valve |ll2 is, therefore, in its central position and the ports |01 and le!) are i closed.

VFigure 4 shows a transmitter unit of the kind shown in Figure 3 Ycoupled to a searchlight, to enable the movements of that searchlight to be duplicated by a second searchlight. No driving mechanism for .eecting movement of the searchlight has been shown, as this may be of any known or convenient type and forms no part of the present invention.

The searchlight 55 is mounted .on a horizontal pivot |56 in a U-shaped bracket |57 itself mounted on a vertical pillar |58 pivotally mounted in a base |59. The body 5| of the transmitter unit is rigidly secured to the base |59 by any convenient means. The hollow piston rod 95 carries, on the boss of the arm |135, horizontal f Sl jectingrfrom the pillar |58. The inner piston rod is similarly connected by a vertical pivot to links |63 connecting it to a member |64 connected by a horizontal pivot to one arm of a bell crank lever |65y mounted on the bracket |51. Theother arm of the bell crank lever |65 is coupled by a universally jointed link |65 to an arm |51 secured to the searchlight |55. Movement of the searchlight about its vertical axis produces movement of both' the hollow piston rod Q5 and the inner piston rod 95, so that no relative movement of the two pistons takes place. Liquid is thus displaced by the hollow piston 93 QFigure 3) into the motor unit, but no liquid is displaced by the piston 94, and the Ysecond searchlight, which is connected t0 the motor unit by linkage similar to that just described,

moves also about its vertical pivot. On the other hand, if the searchlight |55 is moved about the horizontal pivot |56 the inner piston rod 96 is displaced, with relation to the hollow piston rod e5, and the inner piston 543 (Figure 3) of the transmitter unit displaces liquid to the interior of the hollow piston 98 of the motor unit, moving the piston e9 therein and producing corresponding movement of the second searchlight about its horizontal axis. Y

The liquid pressure remote control system described with reference to Figure 3, coupled to searchlights in the manner described with reference to Figure 4, may with advantage be used to ensure the operation in unison of two searchlights which are required to scan a substantially rectangular area continuously. 1 The searchlight l to which the transmitter unit of the control system is coupled is driven in such a way th'atits beam 'B displaced along a path of the form indicated by the line Ile in Figure 5, the beam travelling to and fro on paths Ill displaced laterally one from another, and returning from the end of an extreme lateral path to the corresponding end f of the other extreme lateral path. Each lateral path lli corresponds to a complete stroke of the hollow pistons S3 and Q8, and each short connecting path' llt corresponds t0 a partial stroke of the inner pistons Sli and 951, whilst the long connecting path |73 between the extreme lateral paths |'I| corresponds to a complete stroke of the inner pistons 94 and 9,9. During a complete cycle of movement of the searchlights, the system comprising the'main cylinders and the hollow pistons 93 and 93 is connected lfat each end to the accumulator as many times as there are lateral paths l, and the inner system comprising the hollow pistons and inner pistons is connected at each end to the accumulator once only, at the points VM and I5. Owing to the fact that the stroke of the transmitter pistons is slightly longer than that of the motor pistons, lthe connecting paths W2 of the searchlight connected to the motor unit will be slightly displaced inwardly from the corresponding paths of the searchlight connected to the transmitter unit, but within the area represented by the chaindotted rectangle I`I6 the two searchlights will move in synchronism. Y l

The transmitter unit shown in Figure 3 might be used with two separate motor units each corresponding to one part of the combined motor unit shown in the drawings. Although' the source of pressure liquid has been described in all cases as an accumulator in which pressure is maintained by a pump, it may be a constant-pressure variable delivery pump, the delivery of which falls to zero when no liquid is being fed to the system.

The dual type of remote control system described may be applied to purposes other than that described herein. For example, it might be vused to connect a weapon such as a machine gun or automatic cannon to a, remote sighting device, the sighting device being moved by hand with or without servo-assistance, as desired over the iield of nre which it covers, and the dual remote control system causing the gun to follow the sighting device. Pte-phasing of both systems would then take place at the will of the operator, who, for that purpose, would move the sighting device to a position in which both transmitter pistons were at the same end of their stroke.

What I claim is:

1. A liquid pressure remote control system of the type describedcomprising a transmitter unit including a cylinder having a piston therein, a

source i liquid under pressure, a motor unit including a cylinder having la piston therein, means connecting the transmitter unit to the motor unit, said connecting means and the transmitter and motor units forming a normally closed hydraulic system, manual means for operating said transmitter to put said closed hydraulic system under pressure, `and a valve for controlling the liquid source to said transmitter and motor units, said valve being responsive to the movement of the transmitter piston to at least one end of the transmitter cylinder to cause said valve to open to connect that end of the transmitter cylinder to said pressure source, whereby the stroke of the motor piston if not completed by the movement of the transmitter piston is completed by liquid pressure from said source.

v2. A liquid pressure remote control system of the type described comprising a transmitter cylinder, a motor cylinder, pistons in said cylinders, two conduits, one conduit connecting one end of the transmitter cylinder to one end of the motor cylinder and the other conduit connecting the other end of the transmitter cylinder to the other end of the motor cylinder and which together form a closed hydraulic system, means for producing movement of the transmitter piston in the transmitter cylinder, a source of liquid under pressure, and a valve device operated by the movement producing means when the transmitter piston reaches at least one end of its stroke, to connect the motor cylinder to said source of liquid pressure to cause the motor piston to tend to move in the same direction as it has been moved by the liquid from the transmitter cylinder during the stroke of the transmitter piston just completed.

3. A double acting liquid pressure remote control system of the type described comprising a transmitter cylinder, a motor cylinder, pistons in the cylinders, two pipe-lines, one line connecting one end of the transmitter cylinder to one end of the motor cylinder and the other line connecting the other end of the transmitter cylinder to the other end of the motor cylinder, a reservoir, a source of liquid under pressure, and a valve to be actuated by movement of the transmitter piston to either end of the transmitter cylinder, to connect that end of the transmitter cylinder to which the piston is moved to the liquid pressure source and to connect the other end to the reservoir, whereby the liquid from the source tends to move the motor piston in the same direction as it has been moved by the transmitter piston during its stroke just comple-ted.

4. A double acting liquid pressure remote control system of the type described comprising a transmitter cylinder, a motor cylinder, pistons in the cylinders, two pipe-lines, one line connecting one end of the transmitter cylinder to one end oi the motor cylinder and the other line connecting the other end of the transmitter cylinder to the other end of the motor cylinder, a reservoir having a connection to the transmitter cylinder, a source of liquid under pressure having a connection to the transmitter cylinder, liquid in the two pipe lines and in the ends of the cylinders, and valve means to be actuated by movement of the transmitter piston to `either end of the transmitter cylinder, to connect that end of the transmitter cylinder to which the piston is moved to the liquid pressure source and to connect the other end to the reservoir, whereby the liquid from the source tend-s to move the motor piston in the same direction as it has been moved by the liquid from the transmitter cylinder during the stroke of the transmitter piston just co-mpleted, the effective area of each end of the transmitter piston is equal to the effective area of that end of the motor piston upon which liquid ejected from .the transmitter cylinder by that end of the transmitter piston acts, the total stroke of the transmitter piston being greater than the stroke of the motor piston, the stroke of the motor piston being equal to that part of the stroke of the transmitter piston during which neither end of the transmitter cylinder is connected to the source of liquid under pressure.

5. A double acting liquid pressure remote control system of the type described comprising a transmitter cylinder, a motor cylinder, pistons in the cylinders, two pipe-lines, one line connecting one end of the transmitter cylinder to one end of the motor cylinder and the other line connecting the other end of the transmitter cylinder to the other end oi the motor cylinder, a reservoir having a connection to the transmitter cylinder, a source of liquid under pressure having a connection to the transmitter cylinder, liquid in the two pipe lines and in the ends of the cylinders, and valve means to be actuated by movement of the transmitter piston to either end of the transmitter cylinder, to connect that end of the transmitter cylinder to which the piston is moved to the liquid pressure source and to connect the other end to the reservoir, whereby the liquid from the source tends to move the motor piston in the same direction as it has been moved by the liquid from the transmitter cylinder during the stroke of the transmitter piston just completed, said. Vvalve means controlling the connection ofboth ends of the transmitter cylinder to the source of liquid under pressure, and to the reservoir.

6. A double acting liquid pressure remote control system of the type described comprising a transmitter cylinder, a motor cylinder, pistons in the cylinders, two pipe-lines, one line connecting one end oi the transmitter cylinder t0 one end of the motor cylinder and the other line connecting the other end of the transmitter cylinder to the other end ci the motor cylinder, a reservoir having a connection to the transmitter cylinder, a source of liquid under pressure having a, connection to the transmitter cylinder, liquid in the two pipe lines and in the ends ci the cylinders, valve means to be actuated by movement of the transmitter piston to either end of the transmitter cylinder, to connect that end of the transmitter cylinder to which the piston is moved to the liquid pressure source and to connect the other end to the reservoir, whereby theliquid from the Asource tends to move the motor piston in the same direction as it has been moved by the liquid from the transmitter cylinder during the stroke of the transmit-ter piston just completed, said valve means controlling the connection of both ends of the transmitter cylinder to the source of liquid under pressure, and to the reservoir, the valve being normally biased to an intermediate position in which `both ends of the transmitter cylinder are disconnected both from the source and the reservoir, a pair of stops secured to the valve means, and an arm carried by the transmitter piston for engaging said` stops to move the valve in either direction from its intermediate position to connect one or the other ends of the transmitter cylinder to the vsource or the reservoir.

7. A vdouble acting liquid pressure remo-te `contro-l system of the type described compri-sing a transmitter cylinder, a motor cylinder, pist-ons in the cylinders, two pipe-lines, one line connecting one end of the transmitter cylinder to one end of the motor cylinder, and the other line connecting the other end of the transmitter cylinder to the other end of the motor cylinder, a reservoir having a connection to the transmitter cylinder, a source of liquid under pressure having a connection to the transmitter cylinder, liquid in the two pipe lines and in the ends of the cylinders, a single piston valve' including an operating rod to be actuated by movement oi the transmitter piston to either end of the transmitter cylinder, to connect that end of the transmitter cylinder to which the piston is moved to the liquid pressure source and to connect the other end to the reservoir, whereby the liquid from the source tends to move the motor piston in the same direction'as it has been moved by the liquid from the transmitter cylinder during the stroke of the transmitter piston just completed, said valve controlling the connection of both ends of the transmitter cylinder to the source, and to the reservoir, a spring normally biasing said valve to an intermediate position in which both ends of the transmitter cylinder are disconnected both from the source and the reservoir, a pair of stops on the operating rod, an arm carried by the transmitter piston for engaging said stops .to move the valve in either direction from its intermediate position, a second pair of stops on the operating rod, a third pair of stops radially displaced with respect to said second stops and having the same spacing axially between them as the second stops, and a pair `of washers slidable on the operating rod, said washers being engageable both with the second and third stops, said spring having its ends abutting the Washers tending to urge the same against the second and third stops.

8. A liquid pressure remote control system of the type described comprising a transmitter cylinder, a motor cylinder, pistons in said cylinders, a conduit connecting one end of the transmitter cylinder to one end of the motor cylinder to form a normally closed hydraulic system through which force is transmitted to the piston in the motor cylinder for moving the motor piston in one direction, a spring for moving the motor piston in the oppositeV direction, a source of fluid under pressure, and a reservoir,y valve means for connecting the liquid containing end of the cylinders to the source when the transmitter Ypiston is at the end of its stroke 'during Which'it transfers liquid .to .the motor cylinder, and for 4connecting the said end of the cylinders 12 to the reservoir kwhen the transmitter piston is at the other end of its stroke, said valve means isolating the source of fluid under pressure and the reservoir from the normally closed hydraulic system at all other times.

9. A liquid pressure remote control system according to claim 8, wherein the valve means comprise a single piston valve, three ports axially spaced with respect to the piston valve which controls said ports, the two outer ports arel connected respectively to the source of liquid under pressure and the reservoir, the intermediate port is connected to the liquid containing sides of the cylinders, said valve being normally biased to a central position in which it obturates the intermediate port, and being movable in Veither direction to connect the intermediate port to one or the other of the outer ports.

10. A liquid pressure remote oon-trol system of the type described comprising a transmitter unit including a cylinder, motor cylinders, an -outer -or hollow piston forming a second transmitter cylinder which is reciprocable in the first-named transmitter cylinder, an inner or second piston reciprocable in the second Ytransmitter cylinder or hollow piston, pistons in the motor cylinders, conduits connecting the transmitter unit to the motor cylinders, the pistons in the motor cylinders` being operated by the hollow piston and the second piston vof the transmitter unit respectively, and means being provided to move the transmitter piston-s together or separately to produceL movement of oneor the other of the motor pistons.

11. A liquid pressure remote control system according to claim 10, wherein ,one of the motor pistons is hollow to form a cylinder for the yother motor piston.

l2. A liquid pressure remote control system of the type described comprising a transmitter uni-t including a cylinder, motor cylinders, an kouter or lhollow piston forming a second transmitter cylinder which is reciprccable in the iirst-named transmitter cylinder, an inner or second `piston reciprocable in the second transmitter cylinder or hollow piston, pistons in the motor cylinders, conduits connecting the transmitter unit to the motor cylinders, the pistons in the motor cylinders being operated by the hollow piston and the second piston of the transmitter unit respectively, and means being provided to move the transmitter pistons together or separately to produce movement oi" one or the other of the motor pistons, said motor pistons comprising an outer or hollow piston forming one of said motor cylinders and an inner or second piston reciprocable in said outer piston, a source of fluid under pressure, a reservoir, and a valve for each of the transmitter cylinders, one or `the other of said valves to during the stroke of the transmitter piston just completed.

13. A liquid pressure remote `control system according to claim 12, wherein the valve controlling the connection of the transmitter -cylinder, formed by the interior of the hollow piston, to the source of pressure and to the reservoir is operated to `connect the ends of the said `cylinder 13 to the source and reservoir respectively only when both transmitter pistons are simultaneously at the same end of their strokes.

14. A liquid pressure remote control system of the type described comprising a transmitter unit including a cylinder, motor cylinders, an outer or hollow piston forming a second transmitter cylinder which is reciprocable in the rst-named transmitter cylinder, an inner or second piston reciprocable in the second transmitter cylinder or hollow piston, pistons in the motor cylinders, conduits connecting the transmitter unit to the motor cylinders, the pistons in the motor cylinders being operated by the hollow piston and the second piston of the transmitter unit respectively, and means being provided to move the transmitter pistons together or separately to produce movement of one or the other of the motor pistons, said motor pistons comprising an outer or hollow piston forming one of said motor cylinders and an inner or second piston reciprocable in said outer piston, a source of fluid under pressure, a reservoir, a Valve for each of the transmitter cylinders, one or the other of said Valves to be actuated by movement of either of the transmitter pistons to either end of the cylinder in which it operates to connect that end of the said cylinder to the source of liquid under pressure, and to connect the other end of said cylinder to the reservoir, whereby liquid from the pressure source tends to move the corresponding motor piston in the saine direction as it has been moved by liquid from the transmitter cylinder during the stroke of the transmitter piston `iust completed, each valve having a rod with stops thereon axially spaced, and an arm for each of the transmitter pistons and carried by the respective piston for engaging the stops of the appropriate valve when the piston approaches the end of its stroke, whereby said valve is operated.

15. A liquid pressure remote control system of the type described comprising a transmitter unit including a cylinder, motor cylinders, an outer or hollow piston forming a second transmitter cylinder which is reciprocable in the rst-named transmitter cylinder, an inner or second piston reciprocable in the second transmitter cylinder or hollow piston, pistons in the motor cylinders, conduits connecting the transmitter unit to the motor cylinders, the pistons in the motor cylinders being operated by the hollow piston and the second piston of the transmitter unit respectively, and means being provided to move the transmitter pistons together or separately to produce movement of one or the other of the motor pistons, and connections to the interior of the hollow piston, said connections comprising longitudinal grooves in the exterior of the hollow piston and ports in the wall of the transmitter cylinder, and further ports in the piston connecting the grooves to opposite ends of the interior of said piston.

16. In combination a liquid pressure remote control system of the type described comprising a transmitter unit'J including a cylinder,l motor cylinders, an outer or hollow piston forming a second transmitter cylinder which is reciprocable in the iirst-named transmitter cylinder, an inner or second piston reciprocable in the second transmitter cylinder or hollow piston, pistons in the motor cylinders, conduits connecting the transmitter unit to the motor cylinders, the pistons in the motor cylinders being operated by the hollow piston and the second piston of the transmitter unit respectively, and means being provided to move the transmitter pistons together or separately. to produce movement of one or the other of the motor pistons, said motor pistons comprising an outer or hollow piston forming one of the motor cylinders and an inner or second piston reciprocable in said outer piston, hollow piston rods connected to the hollow pistons, inner piston rods connected to the inner pistons, bellcrank levers connected to the inner rods, a pair of devices each mounted for oscillatory movement in a selected plane, and a pair of supports on which the devices are mounted for oscillation, said supports being mounted for oscillation in a plane perpendicular to the first plane, the hollow piston rods being connected to the supports, and the inner piston rods being connected to the devices through the bell-crank levers.

JOHN KEITH SIMPSON.

Certificate of Correction Patent No. 2,408,003. September 24, 1946.

JOHN KEITH SIMPSON It is hereby certified that errors appear in the printed specieetion of the above numbered patent requiring correction as follows: Column 4, line 32, after piston insert the numeral 29; column 11, line 70, claim 8, for and a reservoir, Valve read erl reservoir, and valve; and that the said Letters Patent should be read With these cor- I'Oeztions therein that the same may conform to the record of the cese in the Patent Signed and sealed this 16th dey of December, A. D. 1947.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents. 

